Navigating with a Map:

Maps are drawings of the terrain on the ground. There are many types of maps. The most common map we use when doing recreational activities such as hiking, biking, or just traversing an orienteering course is a map with topographic symbols. Topographic maps provide contour lines that show the shape of the terrain on the map.

I. Finding and buying a TOPOGRAPHIC map:^3,7

A. Finding maps:

All maps typically are named after a city, a famous landmark, or a peak in the area of coverage. In the US, topographic maps have an index book that contain all topo map published by states. These books are published by the U.S. Geological Survey. Map stores that sell maps usually have these index books. You use these books to locate the map coverage you need. Nowadays, there's probably an online version that you can use to search for your map.

B. Buying maps:

Most topo maps in the US are published by the USGS at Denver, Colorado. After you find the name of the map you want:

(1) The simplest way to get is visit your local sporting goods store or map supply stores like R.E.I., The North Face, Allied Services, Sports Chalet, etc.

(2) The second way is to contact the U.S.G.S. directly at: Maps Sales, Box 25046, Federal Center, Bldg. 810, Denver, Colorado 80225.

II. How to read a map:

In the various camp outings at unfamiliar areas, the big game hunt will apply your skill at using a map and compass. When reading a map, we need to know the following:^3,5

A. Directions on a map:

Most maps have north facing to the top. Along with the general direction there are sometimes grid lines drawn on them. These lines are usually latitude & longitude lines.

Latitude lines run along the East-West direction, and is labeled as North and South heading. 0⁰ starts at the equator and goes up to 90⁰ north at the North Pole; down to the 90⁰ south at the South Pole.

Longitude lines run North-South, and is labeled West and East heading. 0⁰ originates at the Greenwich Meridian in England and ends at the International Date Line with 180⁰ (exactly half way around the world).⁸ Since it is exactly half way around, it can be labeled as West or East.

The intersection of these lines gives you a position on the map.

Newer maps now have UTM grids which are meter base and allow you to pinpoint your position on a map using a set of numbers. [more to follow information to follow in the Appendix section]

B. Date:

Each published map has a date on it.^3,6 If you use a map that is too old, the details on it may not be correct and cause some confusion while navigating.

C. Map-scale:⁷

1:24,000 (1 inch = 2000 ft)
1:25,000 (1 inch ~ 2083 ft)
1:62,500 (1 inch ~ 1 mile)
1:100,000 (1 inch ~ 1.6 miles)
1:250,000 (1 inch ~ 4 miles)

All maps usually have various scales depending on the detail you need. Maps with smaller scales have more detailed information, but cover a smaller area as it is zoomed in closer. Think of it similar to using a magnifying glass. You can see more information but see less of the big picture.

7.5' maps: have scale 1:24,000 (1"=2000ft.), map size 22"x27", and covers an area of 49 to 71 sq. miles. 1⁰x2⁰ maps: scale 1:250,000 (1"~4mi.), map size 22"x32", and cover 4580 to 8669 sq. miles.⁷

D. Land-shape: ^5,7

The elevation (height) of a point on the face of the earth is based on sea-level (0). Contour lines are divided on an even interval [depending on what the scale is]. After each 4 light intermediate contour lines, there is an index contour line marked with a dark line and labeled with its elevation. This enables us to see the elevation easier.

E. Legend symbols:

 

 

Ground Map

F. Finding current position (CP) on a map:

If you want to locate the current position you are standing on a map, we need to base it on at least two other known landmark on the map The more landmark you know, the better the accuracy. This method is known as triangulation.

Example of easy identifiable land features are a hilltop nearby or a lake.

Use the compass to find the bearing of the known points on the map. Transfer the bearing on to the map and draw the lines of the bearing from the known landmark. Your CP will be where the intersection occur on the map..

G. Navigating to a point on the map:

(i Locate your current position (CP): mark this point on the map.

(ii) Find the bearing of the landmark you want to traverse to on the map: Orient the map to face the correct North on the ground. Place the side baseplate of the compass on the map starting from your CP pointing to the landmark.

Lay the compass on the map, so the edge touches the CP and point it toward the landmark. Turn the frame so that the orienting arrow align with the north of the map [use the orienting lines to get more accurate]. The bearing of the objective on the map will follow the DTA. Remember not to move the bezel.

(iii) Go to a landmark: Rotate the compass so that the red arrows [floating needle and orienting arrow] are aligned. Follow the DTA to get to the objective.

H. Finding an object on the map:

(1) Locate your CP: Look on the map and locate your position.

(2) Find the bearing of a distant landmark [see c-2].

After finding the bearing, leave the frame of the compass alone.

(3) Find the location on the map:

• Lay the compass on the map, so that edge of the baseplate touches the location of you CP and the orienting arrow is pointing toward the north of the map. (use the orienting lines for a more precise line up).
• Draw a straight line, from the CP along the edge of the compass.
• Look on this line and you should see the landmark in question.